The invention relates to a transmitter housing.
Transmitters are used in virtually all areas of measurement and control technology. There are a multiplicity of possible uses, both in stockkeeping and in processing industry, e.g. in the chemical industry, in the foodstuffs industry and in the oil industry.
Sensors, e.g. pressure, differential pressure, filling level and/or flow rate measurement sensors, are typically used, said sensors detecting a physical quantity and feeding a sensor signal proportional thereto to a transmitter. The sensor and transmitter are frequently combined in one apparatus comprising both the measurement sensor and the transmitter electronic unit. In the transmitter, the measurement signal is converted into a measurement signal which can be transmitted over relatively large distances. Often the sensor signal is additionally subjected to signal processing in the transmitter, said signal processing serving, e.g. to determine the desired measurement quantity, to eliminate or compensate for measurement errors and/or to improve the signal quality, e.g. by means of noise filters.
Cable lead-ins are regularly provided; external lines can be led into the transmitter through said cable lead-ins and the latter project beyond the transmitter housing. Conventional transmitter housings are in one piece and have a cover. When the cover has been opened, the lines led in through the cable lead-ins are accessible. The electrical connection of the transmitter, e.g. to a supply, to unidirectional signal lines and/or to bidirectional communications lines, is effected when the cover has been opened. In doing so, an electronic unit arranged in the housing is exposed to the influences of the surroundings without any protection. There is the risk, e.g. of moisture attacking the electronic unit and/or of the electronic unit being mechanically damaged. These risks are particularly high when transmitters are installed in the open, e.g. in the event of rain or snow, or when they are used in installations in which aggressive, abrasive or caustic materials are used or processed.
An object of the invention is to specify a transmitter housing in which the transmitter electronic unit is protected against ambient influences even during the electrical connection of the transmitter.
For this purpose, the invention consists in a transmitter housing having
a housing for accommodating a transmitter electronic unit, and
a connection housing,
in which electrical connections that can be connected to external lines are provided and
which is mechanically releasably connected to the housing,
in which a plug-in connection is provided between the housing and the connection housing, via which plug-in connection the transmitter electronic unit can be connected to the connections.
In accordance with a further development of the invention,
the transmitter can be addressed via a bus line,
the bus lines pass through the connection housing, and
branches from each bus line to the plug-in connection are provided in the connection housing.
In accordance with a preferred embodiment of the invention, a seal for protection of the plug-in connection is provided between the housing and the connection housing.
In accordance with a further preferred embodiment, a flame penetration barrier is provided on the housing.
In accordance with a further preferred embodiment, the connections are arranged inside the connection housing and the connection housing has an openable cover through which the connections are accessible.
In accordance with a further preferred embodiment, a cavity remaining in the connection housing is filled with a potting compound.
In accordance with a further preferred embodiment, the transmitter can be addressed via a bus line, the bus lines pass through the connection housing, and a bus driver circuit is arranged in the connection housing.
One advantage of the invention is that the housing together with the transmitter electronic unit can, as required, be exchanged without the transmitter having to be electrically connected anew. This can bring about considerable cost savings, e.g. in the context of exchanging defective apparatuses or during conversion to more modern transmitters.
Regular servicing of the transmitters is necessary in some cases. This is particularly laborious and costly when transmitters are used at poorly accessible locations or in harsh surroundings. In the case of the transmitter housing according to the invention, the housing together with the transmitter electronic unit can be separated from the connection housing in a simple manner and be serviced at a location which is better suited to this purpose.
The invention and further advantages will now be explained in more detail with reference to the figures of the drawing, in which two exemplary embodiments are illustrated; identical elements are provided with the same reference symbols in the figures.
FIG. 1 shows a transmitter housing according to the invention,
FIG. 2 shows individual parts of the transmitter housing of FIG. 1 in an exploded illustration, and
FIG. 3 shows a further transmitter housing, in which housing and connection housing are connected by means of clamping clips.
FIG. 4 shows a cross-sectional view of the transmitter housing along line 4xe2x80x944 of FIG. 2.
FIG. 5 show a cross-sectional view of the connection housing along line 5xe2x80x945 of FIG. 2.